JPH0224963A - Alkaline storage battery and its zinc electrode - Google Patents

Abstract

PURPOSE:To improve the cycle characteristic by providing a Zn electrode made of metal Zn substituted with at least one kind of indium and thallium on the surface and having the average grain size of the preset value or above and Zn oxide having the average grain size of the specific value or below, a positive electrode, and an alkaline electrolyte. CONSTITUTION:An alkaline storage battery provided with a Zn electrode made of metal Zn substituted with at least one kind of indium and thallium on the surface and having the average grain size of 10mum or above and Zn oxide having the average grain size of 1mum or below, a positive electrode, and an alkaline electrolyte is formed. When at least one metal of indium and thallium exists on the surface of the metal Zn, the overvoltage in the reaction that the metal Zn is electrodeposited on the surface is increased. Electrodeposition on the Zn electrode is unified according to this action, the growth of dendritic Zn is suppressed. As a result, the growth of dendritic Zn from the Zn electrode can be suppressed even under the condition of the quick charge/discharge cycle, the alkaline storage battery with excellent cycle characteristic is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION ((a) Industrial Application Field The present invention is applied to alkaline storage batteries using zinc as an active material used in nickel-plated lead storage batteries, silver-zinc storage batteries, etc. The present invention relates to a zinc electrode and an alkaline storage battery equipped with the zinc electrode.

(r: 4) Zinc, which is used as a negative electrode active material, has the advantage of having a high energy density per unit weight and being inexpensive. Because it has characteristics such as high energy density and high operating voltage, it has high expectations as a new general-purpose battery.

However, in this type of alkaline zinc storage TM, when charging and discharging cycles are repeated, the shape of the negative electrode active material changes, resulting in a decrease in battery life. In order to maintain the negative electrode capacity t' even if the shape deformation of the active material progresses, it is effective to include metal zinc as a discharge reserve in the negative electrode active material. Therefore, a method of containing metallic zinc as a discharge reserve in the negative electrode active material was proposed in Japanese Patent Application Laid-Open No. 59-42775.
It is disclosed in the publication No. That is, here, addition of indium etc. 1! A zinc electrode is shown consisting of metal zinc powder having an average particle size of 1 to 6 μm, and zinc oxide powder having an average particle size of 0.1 to 0.5 μm.

According to this method, the additive 710 suppresses hydrogen generation and the growth of dendrites, the degree of mixing of zinc oxide powder and metal zinc powder is high, and a zinc electrode having excellent cycle characteristics can be obtained.

However, when fine metallic zinc powder is used, the electronic conductivity of the active material matrix becomes too high, and the reaction on the electrode surface becomes dominant.As a result, although this is not a problem when charging at a sufficiently low current value, the cycle becomes If rapid light is applied before the reaction progresses, the reaction will concentrate on the electrode surface, resulting in poor adhesion between the active material and the current collector, and the density of the zinc electrode surface will progress, degrading battery characteristics. There is a problem that
Although this problem can be solved by preliminary charging and discharging at a low current value, the necessity of this operation poses a new problem.

For the above reasons, from the perspective of creating a zinc electrode that can withstand rapid charging, it is necessary to construct the zinc electrode with additives, zinc oxide powder, and metallic zinc powder with a relatively large particle size. If it is sufficiently large, the contact between the metal zinc powders will be poor, and as a result, the electronic conductivity of the active material and IJ will not become so large. For this,
Even if rapid charging is performed from the beginning of the cycle, the reaction proceeds from the qM contact surface between the current collector and the active material, and the peeling of the active material and densification of the zinc electrode surface do not occur as in the past. Problems to be Solved However, there is a problem in that metallic zinc powder with a large particle size tends to become a nucleus of one length of dendrite crystals, and internal entanglements within 'am are likely to occur. Therefore, as disclosed in JP-A No. 53-85349, metallic zinc, indium, lead,
There is a method of alloying it with tin, cadmium, thallium, etc. However, even with these methods, the growth of monodendritic crystals cannot be sufficiently suppressed.

Therefore, X@Akira was developed in view of the above points, and has developed zinc electrodes and cycle characteristics for alkaline storage batteries that sufficiently suppress the growth of dendritic zinc even under the harsh conditions of rapid charging. (b) Means for solving the problem The zinc electrode for alkaline storage batteries of the present invention has an average particle size whose surface is replaced with at least one type of moindium or thallium. It is characterized by consisting of metallic zinc with a particle size of 10 μm or more and zinc oxide with an average particle size of 1 μm or less.

In addition, the alkali of the present invention has an average particle size of 1, whose surface is substituted with at least one kind of indium or thallium.
The present invention is characterized by comprising a zinc electrode made of metallic zinc having a particle size of 0 μm or more and zinc oxide having an average particle size of 1 μm or less, a positive electrode, and an alkaline electrolyte.

(E) Effect: When at least 10,000 of either indium or thallium is present on the surface of metal zinc, the overvoltage (charge transfer resistance) of the reaction in which gold FA zinc is electrodeposited on this surface increases. This makes the electrodeposition uniform on the zinc electrode and suppresses the growth of dendritic zinc.

Regarding the alloy powder obtained by melting metal zinc and thallium, indium and thallium exist in the bulk of the powder and are not present in large quantities on the powder surface.
Compared to the present invention, the above-mentioned effects are that it is possible to use large metallic zinc powder because it is difficult for dendrites to grow in metallic zinc powder whose surface is substituted with indium or thallium, such as an extremely small crystal. . In addition, the single-child conduction of the active material matrix and six does not become too large.For this reason, a zinc electrode with less deterioration of characteristics can be obtained even during rapid charging from the early stage of the cycle, and such a zinc electrode can be used. This will improve the cycle characteristics of alkaline storage batteries.

(F) Example (Example 1) Metallic zinc particles having an average particle diameter of 20 μm were immersed in an indium chloride solution of 0.1 μm for 2 hours.

Filtered. Subsequently, the powder was immersed in a solution of 0.1 mol of hydroxide, washed with water, and dried to obtain a metallic zinc powder with indium added to its surface. At this time, the number 71 [1 (substitution t) of indium is relative to the weight of the metal zinc powder,
Next, metal zinc particles of about 0.596 mm or an average particle size of 20 μm are immersed in a 0.03 mol thallium chloride solution for 2 hours, filtered, and similarly KO, 1 mol sodium hydroxide. A metal zinc powder to which thallium was added was obtained by immersing it in a solution, washing it with water, and drying it.□The amount of thallium added at this time was about 0.5% based on the weight of the metal zinc powder.

Further, metal zinc particles having an average particle size of 20 μm were immersed for 2 hours in a solution of 0.03 mol of tHe thallium, and then further immersed for 2 hours in a solution of 0.1 mol of indium chloride. By carrying out the operation, a metallic zinc powder to which 0.5916 sts of indium and thallium were each added was obtained (9) Furthermore, a metallic zinc powder to which indium, thallium and lead were added was obtained in the same manner, and these respective metallic zinc powders, Mix zinc oxide and indium hydroxide as an additive in a ratio of 30:68:2, add PTFE dispersion and water, and mix 1 t.
I did i'r and created paste i.

This base was crimped onto the +-1 current collector to obtain a zinc electrode.

The average particle size of the zinc oxide used here is 1 μm or less, and a zinc electrode using metal zinc substituted with or added with n-indium, which is usually used in this range, is used as zinc electrode A of the present invention, thallium Zinc electrode using metallic zinc substituted or added ffi' , the zinc electrode using added metal zinc was used as the zinc electrode of the present invention, and the average particle size was 20 μm without adding indium or thallium.
Zinc electrode E was used as a comparative example.

By combining these zinc electrodes and sintered two Kel electrodes,
Each cylindrical sealed nickel-zinc battery was fabricated as an IO cell. And, the present invention @aa, l), C, respectively.
d, and these batteries a to θ of zero order with pond e as the comparison?
A charge/discharge cycle test was conducted using the battery. The charging and discharging conditions are as follows: 96 charges with IC current, followed by 100% discharging with IC current, and a rapid charge/discharge cycle is repeated until the -capacity reaches 6096 times, which is the initial battery capacity.
The cycle life is defined as the following:

Table 1 shows the cycle lives of batteries a to θ using zinc electrodes A-Et- under each of the above conditions.

Table 1 All of the hollow + C2 invention batteries a to d shown in Table 1 were 30
A cycle life of 0 cycles or more has been obtained, but the cycle life of the comparison battery e is 55 cycles, which is due to the furnace □
This is thought to be due to the fact that metal zinc, which has a relatively large particle size without addition of indium or Idyllium, is used, so this metal zinc becomes a nucleus, and dendritic crystals grow, creating an internal snow road. It will be done.

(5j! Example 2.) Next, average particle diameters of 2 μm, 5 μm, 10 μm, 2Q μm,
A metal zinc powder was obtained in which 0.5% or more of each of indium and thallium was added to the signal of 50 μm, LOOjJm, 2 (10 am).

A zinc electrode and a test battery were prepared in the same manner, and a cycle test was conducted under the same conditions as in Example 1.
Based on the cycle life, the particle size of the metal zinc powder to which indium and thallium were completely added was evaluated. The result was gold, as shown in Figure 1.

From the results shown in FIG. 1, it can be seen that the average particle size of the metal zinc powder, which exhibits excellent characteristics even in the rapid charging test, is 10 μm or more. Kinzana fE again! If it is a metallic zinc powder with all indium and thallium added to the surface, 200
Even with particles having a large particle size of μm, the growth of dendrites is suppressed, resulting in excellent characteristics.

(g) Effects of the Invention According to the present invention, it is possible to suppress the growth of dendritic zinc from the zinc electrode even under the harsh conditions of rapid charge/discharge cycles, and it is possible to provide an alkaline storage battery with excellent cycle characteristics. Therefore, its industrial value is extremely large.

[Brief explanation of the drawing]

Figure 1 shows the average particle size of the metal zinc powder constituting the zinc electrode according to the present invention, and! It is a figure showing the relationship with the cycle life of a pond.

Claims (2)

[Claims] (1) Metallic zinc with an average particle size of 10 μm or more whose surface is substituted with at least one type of indium or thallium;
A zinc electrode for alkaline storage batteries consisting of zinc oxide with an average particle size of 1 μm or less. (2) Equipped with a zinc electrode made of metallic zinc with an average particle size of 10 μm or more and zinc oxide with an average particle size of 1 μm or less, whose surface is substituted with at least one type of indium or thallium, a positive electrode, and an alkaline electrolyte. alkaline storage battery.