JPS61118967A - Alkali-zinc storage battery - Google Patents

Abstract

PURPOSE:To effectively restrain the growth of zinc dendrite to obtain a longer cycle life by using a zinc electrode including an active material mixture in a negative electrode. CONSTITUTION:In a nickel-zinc storage battery including a negative electrode 1, a positive electrode 2, a separator 3 and a layer 4 for holding liquid, a zinc electrode including an active material mixture containing a zinc alloy containing indium and gallium, a zinc oxide, an oxide or a hydroxide of gallium is used in a negative electrode 1, Indium and gallium in the zinc alloy is set to 0.5-5wt%, respectively, and further a total amount of an oxide or a hydroxide of indium and an oxide or a hydroxide of gallium is set to 1-10wt% of the active material mixture, and furthermore the zinc alloy in the active material mixture is set to 5-100wt% of the zinc oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to alkaline zinc storage batteries that use zinc as a negative electrode active material, such as nickel-zinc batteries and silver-zinc batteries.

(b) Conventional technology Zinc as a negative electrode active material has the advantage of having a high energy density per unit weight and being inexpensive, but on the other hand, zinc is eluted into the electrolyte as zincate ions during discharge, and during charging, zinc This is because the ions become zinc and are deposited in a dendritic or spongy form.

Electrodeposited zinc grows and penetrates the separator and comes into contact with the counter electrode, which tends to cause internal short circuits.Also, it self-discharges in the alkaline electrolyte and generates hydrogen gas, resulting in a short cycle life.

In order to improve this cycle life, Japanese Patent Application Laid-Open No. 51-123
No. 65 proposes metals such as indium and thallium or oxides of these metals as additives to zinc electrodes. Furthermore, Japanese Patent Application Laid-Open No. 53-85349 proposes the use of a zinc alloy alloyed with a metal such as indium as a negative electrode active material. In this way, by adding indium, which has a high water-purple overvoltage and is nobler than the oxidation-reduction potential of zinc, to the zinc electrode, the growth of zinc dendrites can be suppressed, suppressing the deformation of the electrode plate and improving the cycle life. You can measure the example. However, when metals such as indium or metal oxides are contained in zinc electrodes as additives, the additives are relatively easily eluted into the electrolyte, so as they are repeatedly dissolved and precipitated by charging and discharging, the additives become unevenly distributed. Therefore, deformation of the electrode plate occurs from the part where no additive is present. In addition, when a zinc alloy is used as an active material, the uneven distribution of metals such as indium alloyed with zinc is suppressed, but by forming a single alloy, the activity of zinc is lower than when the above metals or metal oxides are added. did.

(c) Problems to be Solved by the Invention The present invention aims to effectively suppress the growth of zinc dendrites and obtain a longer cycle life.

B) Means for Solving the Problems The alkaline zinc storage battery of the present invention contains a zinc alloy containing indium and gallium, zinc oxide, an oxide or hydroxide of indium, and an oxide or hydroxide of gallium. A zinc electrode with an active material mixture containing the active material mixture is used as the negative electrode, and the indium and gallium in the zinc alloy are each 0.5 to 5% by weight of the alloy, and the indium oxide or hydroxide and When the total amount of gallium oxide or hydroxide is 1 to 10 weight tS of the active material mixture, and the zinc alloy in the active material mixture is 5 to 100 weight tS of the zinc oxide, further effects can be obtained. It is something to play.

(e) Effect Zinc alloys containing indium and gallium added to zinc electrodes are less likely to cause uneven distribution of indium and gallium in the zinc electrodes than indium and gallium oxides or hydroxides. The effect can be maintained for a long period of time.

In addition, if the amount of indium and gallium in the alloy is too large, the activity of zinc forming the alloy will be reduced and the charge/discharge efficiency will be reduced, and if the amount is too small, the effect of indium and gallium in the alloy will be negligible. Therefore, it is necessary that the amount of each of these elements be 0.5 to 5% by weight of each alloy.

When indium and gallium oxides or hydroxides are added to the zinc electrode in addition to the zinc alloy, the cycle life is increased compared to when only the zinc alloy is added and when only the indium and gallium oxides or hydroxides are added. Extends. The reason for this is not clear, but it is thought to be due to the synergistic effect of these zinc alloys and the oxides or hydroxides of indium and gallium. At this time, if the total amount of indium and gallium oxides or hydroxides added to the zinc electrode is too large, the effective amount of active material in the zinc electrode will decrease, the concentration of the additive will increase, and the active material will become inactive. This is because it becomes easier to activate and causes a decrease in battery capacity.

Preferably, the amount of zinc alloy in the active material mixture is between 1 and 100% by weight; too much zinc alloy in the active material mixture improves the conductivity and the effective amount of active material, but decreases the amount of zinc oxide and reduces the content of the electrode. Because the liquid property decreases and has a negative impact on battery performance,
5 to 100 parts by weight of zinc oxide is preferred.

(f) Example A mixed powder consisting of 94% by weight of zinc powder, 3% by weight of indium powder, and 3% by weight of gallium powder was melted in a crucible to obtain a zinc alloy containing indium and gallium. The alloy is ground to obtain a powder of 100 to 300 mesh passes. The melting temperature is generally preferably 400 to 600°C, and the melting temperature was 500°C when producing the zinc alloy. Indium and gallium prepared in this way were each
Zinc alloy powder containing 20% by weight, 73% by weight of zinc oxide powder, 1% by weight of indium oxide powder as an additive.
Water is added to a mixed powder consisting of 1% by weight of gallium oxide powder and fluororesin powder as a binder, and the mixture is kneaded and made into a sheet by rollers. This sheet-like active material mixture is then made into a porous material made of copper or the like. It is attached to both sides of a current collector, pressure-molded, and then dried to produce a zinc electrode. Next, the zinc electrode was combined with a sintered nickel electrode to produce a nickel-zinc storage battery (6) as shown in FIG. 1st
In the figure, (1) is a zinc electrode as a negative electrode, (2) is a nickel i as a positive electrode, (3) is a sepanator, and (4) is a liquid retaining layer.

(5) is the battery case, (6) is the battery case lid, (7) is the positive terminal, (
8) is a negative bridge terminal.

For comparison, the hand-chain alloy containing indium and gallium was replaced with metal zinc, and the other conditions were as in the battery (8).
Same as nickel-zinc storage battery (B).

Furthermore, without adding indium oxide and gallium oxide as the additives, zinc oxide'! A nickel-zinc storage battery (C) was prepared by increasing i and using the same conditions as battery (4) above.

Figure 2 shows the battery (4) according to the present invention and the comparative battery () and (
0), the battery voltage is 1.0 after charging at 150 mA for 6 hours and discharging at 150 mA. The measurements were taken by repeatedly charging and discharging under cycle conditions in which the discharge was stopped when Ov was reached. '@2 As is clear from Fig. 2, it can be seen that the battery of the present invention (4) has improved Benaigle characteristics compared to the comparative batteries (B) and (C).

Next, tests were conducted to determine the optimal values for the ratio of the components of the zinc electrode and the ratio of indium and gallium in the zinc alloy. This result t- will be omitted and explained below.

[Test 1] Zinc alloy powder, which is an alloy of zinc, indium, and gallium, was prepared by varying the t of indium and gallium with respect to the superposition of the alloy, and 20% by weight of the thus prepared zinc alloy powder and zinc oxide were mixed. Completely mix 75% by weight of powder and 5% by weight of fluororesin powder as a binder, use the mixed powder thus obtained to produce a zinc electrode in the same manner as described above, and use this zinc electrode to form a nickel-zinc electrode. A storage battery was created. Figure 'L%3 is a diagram showing the cycle life. In the figure, the amounts of indium and gallium added are expressed as the total amount of indium and gallium in the alloy relative to the zinc alloy, and indium and gallium are added to the alloy at the same rate. Moreover, the cycle life is the number of cycles when the battery container becomes less than 50 cm of its initial capacity after repeated charging and discharging under the above-mentioned cycle conditions. From the results shown in Figure 3, the total amount of indium and gallium in the zinc alloy is 1 to 10 weights ff15J of the zinc alloy, in other words, the amounts of indium and gallium in the zinc alloy are 0.5 to 5 weights of the zinc alloy, respectively. %, it can be seen that a good cycle life can be obtained.

[Test 2] Zinc gold 30 layers containing indium and gallium at 1% of the alloy, respectively, and zinc oxide X layer width.

A mixed powder consisting of indicum oxide Y as an additive, gallicum oxide Z as an additive, and 5 im% of a fluororesin as a binder was mixed with X as shown in (7) to (g) in Table 1.
Produced by varying the Y and Z values.

A zinc electrode was produced using the mixed powder thus obtained in the same manner as described above, and a nickel-zinc storage battery was also produced using this zinc electrode. FIG. 4 is a drawing showing the dust and cycle life of the product, and the cycle life was measured using the same method as Test 1. It can be seen from FIG. 4 that a good cycle life can be obtained when the total amount of indium oxide and gallium oxide as additives is 1 to 10 grams of the active material mixture.

Table 1 [Test 3] In Tests 1 and 2, the concentration of indium and gallium in the zinc oxide used in zinc electrodes and the total amount of indium oxide and gallium chloride as additives were known, so we further determined the amount of zinc used in zinc electrodes. Use the right amount of alloy.

Zinc mixture containing triple concentrations of indium and gallium, zinc oxide W term @ 2, 2.5 indium oxide as additive, 2.5 gallium oxide, and binding. As shown in Table 2, mixed powders were prepared from the resin powder 5-gokuchi as an agent by varying the values of V and W as shown in Table 2).

Using the thus obtained mixed powder, a zinc electrode was prepared in the same manner as described above, and a nickel-zinc storage battery was also prepared using this zinc electrode. FIG. 5 is a drawing showing the cycle life, and the cycle life was measured by the same method as Test Riding 1. From Figure 5, it can be seen that the zinc casing can have a good cycle life for 5 to 100 cycles of one zinc oxide.

Table 2 Incidentally, in the above example, acid fine diam and gallium oxide were used as additives, but the same effect can be obtained by using water hydroxide and gallium hydroxide instead.

(G) Effects of the Invention The uninvented alkaline zinc storage battery uses an active material containing a zinc alloy containing indium and gallium, zinc oxide, an oxide or hydroxide of indium, and an oxide or hydroxide of gallium. Since the zinc electrode with the mixture is used as the negative electrode, it is effective due to the synergistic effect of the zinc alloy containing indium and gallium, the oxide or hydroxide of indium, and the oxide or hydroxide of gallium. Dendritic growth of zinc and changes in the shape of zinc poles were observed to be suppressed by Yohata fishing.

Longer cycle life can be obtained.

[Brief Description of the Drawings] Figure 1 is a sectional view of an alkaline zinc storage battery according to an embodiment of the present invention, Figure 2 is a cycle characteristic diagram of the battery of the present invention (4) and a comparative battery (-), Figure 3 is a diagram showing the relationship between the amount of indium and gallium in the zinc alloy contained in the zinc electrode and the cycle life of the battery. FIG. 4 is a diagram showing the relationship between the ratio of the total amount of indium oxide and gallium oxide to the active material mixture and cycle life, and FIG. 5 is a diagram showing the relationship between the ratio of zinc alloy to zinc oxide and cycle life. (1)...Zinc%, (21...Nickel electrode, (
3)...Sebaret-3)(4)...liquid retaining layer, (5) battery case, (6)...container lid, (7)...positive scratch terminal, (
8)...Negative terminal.

Claims (4)

[Claims] (1) A zinc electrode comprising an active material mixture containing a zinc alloy containing indium and gallium, zinc oxide, an oxide or hydroxide of indium, and an oxide or hydroxide of gallium is used as a negative electrode. Alkaline zinc storage battery. (2) Claim No. 1, wherein indium and gallium in the zinc alloy each account for 0.5 to 5% by weight of the alloy.
) Alkaline zinc storage battery described in item 2. (3) The alkaline zinc storage battery according to claim (1), wherein the total amount of the indium oxide or hydroxide and the gallium oxide or hydroxide is 1 to 10% by weight of the active material mixture. . (4) The alkaline zinc storage battery according to claim (1), wherein the zinc alloy in the active material mixture is 5 to 100% by weight of the zinc oxide.