JPS6196666A - Alkaline zinc storage battery - Google Patents

Abstract

PURPOSE:To obtain an alkaline zinc storage battery having long cycle life by specifying the kind and the amount of additives of a zinc electrode. CONSTITUTION:Oxides or hydroxides of indium and thallium, and at least one oxide or hydroxide selected from a metal group comprising gallium, cadmium, lead, tin, bismuth and mercury are contained in a zinc electrode as additives. The total amount of additives is limited to 1-15wt% of the zinc electrode. Preferably, the content of oxides or hydroxides of indium and thallium is specified to 1/6-1/9 of the oxide or hydroxide selected from the metal group. By this mixing ratio, the uneven distribution of indium and thallium is suppressed and inactiveness of zinc active material is also suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Industrial Application Field The present invention relates to an alkaline zinc storage battery using zinc as the negative electrode active material, such as a nickel-zinc storage battery or a silver-zinc storage battery.

(b) Conventional technology Zinc as a negative electrode active material has the advantage of having a high energy density per unit type and being inexpensive, but on the other hand, zinc dissolves into the alkaline electrolyte during discharge and becomes one zincate ion during charging. At time L', these zincate ions are deposited on the surface of the zinc electrode in a dendritic or spongy form, so when charging and discharging tk are repeated, the deposited zinc comes into contact with the counter electrode through the separator ti, causing an internal short circuit, which shortens the cycle life. There is a short drawback.

In order to improve this cycle life, it has been proposed to drop various metals, metal oxides or hydroxides into the zinc electrode. As a supplement to this zinc electrode,
In Japanese Patent Application No. 1-56450, indium hydroxide or indium oxide is used, and in Japanese Patent Application No. 58-62634, thallium oxide is used as a zinc hydroxide and indium oxide or hydroxide as a caloric compound. It has been proposed to add it to the pole. Indium and thallium have a high hydrogen overvoltage and are nobler than the oxidation-reduction potential of zinc, so they can suppress the formation of zinc dendrites and suppress plate deformation. Batteries with zinc electrodes containing hydroxide have significantly improved cycle life because the addition of indium suppresses the dissolution of thallium into the electrolyte. Even if a lead electrode (with thallium oxide or hydroxide) is used, if a long charge/discharge cycle is performed, not only the zinc active material but also indium and thallium will be involved in charge/discharge, and their distribution will become uneven. At the same time, the deactivation of the zinc active material progressed, and the effective reaction area of the main electrode decreased, resulting in a decrease in battery resistance.

(c) Problems to be solved by the invention This invention solves the problem of indium and thallium oxide by examining the additives and amounts added to the zinc electrode! Alternatively, it is an attempt to obtain an alkaline zinc battery having a longer cycle life than an alkaline battery formed by adding hydroxide to the zinc electrode.

B.) Means for solving the problem The alkaline zinc storage battery according to the present invention contains as additives an oxide or hydroxide of indium, an oxide or hydroxide of thallium, and gallium, cadmium, lead, tin, bismuth, mercury. A zinc electrode containing at least one oxide or hydroxide selected from the metal group consisting of: and the total amount of the additives is 1 to 15% by weight based on the zinc electrode, preferably The blending ratio of the oxide or hydroxide of indium and thallium to at least one oxide selected from the metal group is 176 to 9.

(E) Effect The above means suppresses uneven distribution of indium and thallium, and also suppresses deactivation of the zinc active material.

(f) Example 70% by weight of zinc oxide powder, 20% by weight of zinc powder, 1.5% by weight of indium oxide as an additive, 2% of thallium oxide
．． 5% by weight of gallium oxide, 1% by weight of gallium oxide, and 5 layers of fluororesin powder as a binder, water is added and kneaded, and the resulting sheet is formed into a sheet using a roller. Zinc electrodes are produced by adhering to both sides of the electrode, press-molding, and drying. By combining the zinc electrode thus produced and a known sintered nickel electrode, an uninvented nickel-zinc storage battery (Al'e) was assembled. Zinc electrode, (21 is a nickel electrode, (1 is a separator, (4) is a liquid storage j-1 (51 is a battery case, (6) is a Fi tank lid, +71 (81 is a main and negative terminal).

In addition, a comparative battery (G) 1 was fabricated except that the additives in the zinc electrode in the above Example were replaced with 2% by weight of indium oxide and 6% by weight of thallium oxide.

Figure 2 is a cycle characteristic diagram of a battery according to the present invention (At) and a comparative battery.The cycle conditions were to charge at 150mA for 6 hours, then discharge at 150ffiA, so that the battery voltage was 1, O
The discharge is stopped when the voltage reaches v. As is clear from FIG. 2, the battery according to the present invention (At is the comparative battery (B
It can be seen that the cycle life is longer than that of 1.

Comparative battery (Bl zinc electrode) When the charge/discharge cycle becomes long, the additives indium and thallium also participate in charge/discharge.
Due to the uneven distribution of these additives, zinc dendrites grow in areas where additives are not present, and the active material becomes inactivated, reducing the effective reaction area of the zinc electrode, resulting in capacity deterioration. It is thought that this happened relatively quickly. On the other hand, the battery according to the present invention (the zinc electrode of Al is used as an additive)
By adding gallium oxide in addition to the indium oxide and thallium oxide, uneven distribution of the indium and thallium is suppressed, and deactivation of the zinc active material is also suppressed. It is thought that the cycle life was improved because the effect was maintained.

Next, the total amount of additives added to the zinc electrode will be explained.

Zinc oxide powder W wt%, zinc powder 15 wtffi'%, indium oxide X wt% as additive, thallium oxide 7
A mixed powder consisting of 2% by weight of gallium oxide and 5% by weight of fluororesin powder as an additive was used in place of the mixed powder used when manufacturing the zinc pole in the above example, and W ,x%Y,Z 4if! Batteries were produced in the same manner by changing the values as shown in (7) to Examples in Table 1. Note that the mixing ratio of the additives is kept constant: X/Y=1, (X+Y)/Z=4. Mixing ratio of thallium oxide to indium oxide (T l 205 / I n 20 &
) was set to 1 because a good cycle life was obtained within the range.

Figure 3 shows the total amount of additives (total weight percent of indium oxide, thallium oxide, and gallium oxide) in the zinc electrode using these batteries.
) is a drawing showing the results of measuring the cycle life of a battery, where charging and discharging are repeated under the above-mentioned cycle conditions, and when the discharge capacity reaches 50% of the initial capacity, the charging and discharging cycle is terminated and the cycle life is determined. did. As is clear from FIG. 5, it can be seen that the battery containing additives in a total amount of 1 to 15% by weight has a long cycle life and is good.

Furthermore, the blending ratio of additives and the metal oxide that has the same effect as potassium oxide added together with indium oxide and thallium oxide will be explained below.

■ A mixture of 80% by weight of zinc oxide powder, 10% by weight of zinc powder, 1 J$ of indium oxide as an additive, yM*% of thallium oxide and zNt% of gallium oxide, and 5% by weight of fluororesin powder as a binder. Using powder, the values of x, y, and z are determined by C in Table 2, with the total amount of additives being 5% by weight.
Zinc electrodes were prepared in the same manner as described above by changing the conditions as shown in FIGS.

Let this battery be (al).

Table 2 (2) The same battery (bli) was prepared except that saponified cadmium was used instead of gallium oxide in the above battery (al).

(2) A battery (let) was produced which was the same as the simple battery (L) except that lead oxide was used instead of gallium oxide.

(◇ A battery (di) was fabricated using tin oxide instead of potassium oxide in the battery (at), which was otherwise the same.

(2) A battery (re)'(e) was fabricated using bismuth oxide instead of potassium oxide in the battery (al), but otherwise the same battery.

(2) A simple battery (/'1 was prepared using mercury monoxide instead of gallium oxide in the Al, but otherwise the same battery).

Figure 4 shows the blending ratio of additives for these 'electrocardiograms' (al to φ zinc electrodes [t(zl) of the metal oxides such as gallium oxide
The sum of indium oxide and thallium oxide for −j(x
This is a drawing showing the cycle life of the 'tT1 pond with respect to the mixing ratio of +y), and the cycle life was determined using the same operation f as described above. From the fourth factor, a battery in which gallium oxide is added to the zinc electrode in addition to indium oxide and thallium oxide (Similar to AL, a battery in which various metal oxides are added instead of gallium oxide (the cycle life of BL to (/1) is improved. This shows that saponified cadmium, lead oxide, tin oxide,
It is believed that bismuth oxide and mercury oxide, like gallium oxide, suppressed the uneven distribution of indium and thallium and also suppressed the inactivation of the zinc active material. Also the fourth
From the figure, the blending ratio of additives used in these zinc electrodes (X
+Y/z), it can be seen that the cycle life of the battery is long and good within the range of 1A to 9C.

In addition, in the above implementation 1, the additive is in the oxide form 1; i%-'
(Although it was added to the zinc electrode, the same effect can be obtained by using an oil agent in the form of hydroxide.

(G) Effects of the Invention The alkaline zinc storage battery according to the present invention uses indium oxide or hydroxide, thallium oxide or hydroxide, and metals made of gallium, cadmium, lead, tin, bismuth, and mercury as additives. Since it is equipped with a zinc electrode containing at least one kind of oxide or hydroxide selected from the group, and the total amount of the additive is 1 to 15% by weight based on the zinc electrode, charging and discharging can be repeated. The maldistribution of indium and thallium that occurs when the indium and thallium are heated is suppressed, and the deactivation of the zinc active material is suppressed, thereby making it possible to provide an alkaline zinc storage battery having a longer cycle life. Furthermore, if the total compounding ratio of the oxides or hydroxides of indium and thallium to at least one kind of oxide or hydroxide selected from the metal group is 1A to 9, the above effects can be further enhanced. It is possible to draw it out.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an alkaline zinc storage battery according to an embodiment of the present invention, and FIG. 2 is a longitudinal cross-sectional view of an alkaline zinc storage battery according to an embodiment of the present invention.
FIG. 6 is a diagram showing the cancerous cycle life of the zinc electrode. Tll...Zinc electrode, (21...Nickel electrode, +
31...Ceno(rate), 14+-...liquid retaining layer, +
51...Battery container, (61...Battery container lid. +71 (81, - positive, ° negative terminal.

Claims (2)

[Claims] (1) The main component is zinc or zinc oxide, and the additives are selected from the metal group consisting of indium oxide or hydroxide, thallium oxide or hydroxide, and gallium, cadmium, lead, tin, bismuth, and mercury. 1. An alkaline zinc storage battery comprising a zinc electrode containing at least one oxide or hydroxide, wherein the total amount of the additives is 1 to 15% by weight based on the zinc electrode. (2) The total blending ratio of the indium oxide or hydroxide and the thallium oxide or hydroxide to at least one oxide or hydroxide selected from the metal group is 1/6 to 9. An alkaline zinc storage battery according to claim (1).